Matthew G. Whitaker, installed in the job by President Trump to replace Jeff Sessions, was asked in 2014, during an ill-fated run in the Republican senatorial primary in Iowa, about the worst decisions in the Supreme Court’s history. Whitaker’s answer, to an Iowa blog called Caffeinated Thoughts, was chilling.

“There are so many,” he replied. “I would start with the idea of Marbury v. Madison. That’s probably a good place to start and the way it’s looked at the Supreme Court as the final arbiter of constitutional issues. We’ll move forward from there. All New Deal cases that were expansive of the federal government. Those would be bad. Then all the way up to the Affordable Care Act and the individual mandate.”

Reasonable people can differ over the constitutionality of the Affordable Care Act. Maybe there’s some space to debate the New Deal-era cases that cemented the authority of the regulatory state. But Marbury? This is lunacy. For any lawyer — certainly for one now at the helm of the Justice Department — to disagree with Marbury is like a physicist denouncing the laws of gravity.

Decided in 1803, at the dawn of the new republic, Marbury v. Madison is the foundational case of American constitutional law. It represents Chief Justice John Marshall’s declaration that the Supreme Court possesses the ultimate power to interpret the Constitution and determine the legitimacy of acts of Congress.

In Marshall’s famous words, “it is emphatically the duty of the judicial department to say what the law is.” The untested new Constitution provided that the Supreme Court possessed the “judicial Power of the United States,” but it did not define what that power entailed.

“With one judgment . . . Marshall would chisel judicial review into the American system,” Cliff Sloan and David McKean explain in their book, “The Great Decision.” The ruling, “asserting clearly and unequivocally that the Supreme Court did indeed possess the power to strike down an Act of Congress as unconstitutional . . . laid the foundation for the American rule of law.”

This is not a controversial position, at least in mainstream legal thought. On occasion, Supreme Court nominees, including Antonin Scalia and Neil M. Gorsuch, declined to state their agreement with Marbury. But this coyness is not because they differ with the ruling; rather, it is because they fear stepping onto the slippery slope of assessing past cases.

More commonly, Marbury is the uncontested subject of lavish judicial praise. Chief Justice John G. Roberts Jr. endorsed it during his confirmation hearings, and expanded on that view in a 2006 C-SPAN interview. Marshall’s decision meant “we have the courts to tell what [the Constitution] means and what’s binding on other branches,” Roberts said, “and that important insight into how the Constitution works has been, I think, the secret to its success.”

But if you think, as Whitaker seems to, that Roberts is too much of a squish (“he’s not a good person to point to when it comes to actually just calling balls and strikes in practice,” Whitaker said of Roberts in the 2014 interview), consider Roberts’s predecessor as chief justice, William H. Rehnquist. In his book on the Constitution, Rehnquist described Marbury as “the linchpin of our constitutional law.”

Yet we seem to have, as the nation’s chief law enforcement officer, a man who begs to differ. Is this still his position? If so, how does that view — that the court in Marbury was too assertive in exercising its power — square with Whitaker’s simultaneous beef that the court was inadequately assertive in striking down laws during the later New Deal era and when dealing with the Affordable Care Act?

That’s not the only troubling question about Whitaker. During a 2014 Senate debate sponsored by a conservative Christian organization, he said that in helping confirm judges, “I’d like to see things like their worldview, what informs them. Are they people of faith? Do they have a biblical view of justice? — which I think is very important.”

At that point, the moderator interjected: “Levitical or New Testament?”

“New Testament,” Whitaker affirmed. “And what I know is as long as they have that worldview, that they’ll be a good judge. And if they have a secular worldview, then I’m going to be very concerned about how they judge.”

Marbury was wrong. Religious tests for judges. If you thought the big worry about Whitaker was how he would handle special counsel Robert S. Mueller III, that might be just the beginning.